Astronomical understanding registered dramatic gains between
1910 and 1950. Most especially, astronomers came to regard
most stars as plasma spheres powered by nuclear reactions
deep within their interiors and to view the galaxy as one
among myriads in an expanding universe. In discussing why
those working on astronomical problems during this period
were so successful, I argue that they had better tools than
their predecessors-not only bigger telescopes but also more
puissant physical theories.

The author(s) of this abstract have provided an email address for comments about the abstract: hufbauer@uci.edu